Not trying to nitpick, and not arguing with the sense of sadness you feel -- I sympathize -- but I wouldn't call "passively keeping in touch" with thousands of people "relationships." It's something, but I'm not sure what, it seems like we may not have a good word for "casual strangers," the level of familiarity beneath acquaintance that we know because we met them once and then know only what they post in one social media database or another.

Also, to be honest, I felt the way you did before I deleted a twitter account with about 2k following and 10k followers. I felt like it was dominating my attention, and that made me mad. In a fit of pique I deleted it and it's almost funny how quickly I realized I didn't know any of them, and the passive consumption of their social media database entries was scratching some kind of itch but the same one I get from e.g. binging Star Trek series.

Very strange all around.